Objectives and Specific Aims The goal of cancer treatment is cure without morbidity. Radiation can be an effective locoregional cancer treatment. While any tumor can be killed with enough radiation, any normal tissue can also be injured with sufficient dose to a given volume. The challenge is to deliver the appropriate dose to only those tissues containing tumor. Protons, with no exit dose beyond the target, irradiate less normal tissue than comparable photon (X-ray) fields. This can improve the therapeutic ratio of cure probability to complication risk. While many patients have been treated with protons with impressive clinical results in a number of disease sites, we believe that research can enable and enhance the use of protons in other disease sites. The objective of this multi-institutional program project is to apply advanced proton radiation planning and delivery techniques to improve outcome for patients with non-small cell lung cancer, liver tumors, pediatric medulloblastoma and rhabdomyosarcoma, spine/skull base sarcomas, and paranasal sinus malignancies. We hypothesize that through better use and understanding of the proton range in tissue, and study and management of motion and anatomic changes in the tumor and normal tissues, we can deliver higher precision proton therapy to further improve target coverage and/or reduce dose to nearby critical structures. To test this hypothesis, we propose four integrated projects: (1) Proton Dose Escalation and Proton vs. Photon Randomized Trials for the Treatment of Nonsmall Cell Lung Cancer, (2)lmproving the Therapeutic Ration of Proton Radiation Therapy in Challenging Clinical Sites, (3) Reducing Range Uncertainties in Proton Radiation Therapy, (4) Achieving What-You-See-ls-What-You-Get in Proton Radiation Therapy. The proton physical interactions sufficient to allow smallerspecific aims are to (1) develop an understanding of safety margins as well as more robust and conformal dose distributions, allowing protons to more nearly meet their full potential, and to verify that these advantages can be reliably achieved; (2) use these advantages in randomized clinical trials of protons vs. photons in lung cancer; and (3) to use these advantages in the proton therapy of a number of tumor sites for which protons are judged to have an increasingly important role and which have proven problematic for clinicians in the past.